Powders are usually manufactured by grinding larger stock of the same material. One example is the manufacture of powder for use in producing a protective and decorative coating. In use the powder is first electrostatically sprayed onto the article to be coated. The temperature of the article is then raised in an oven to stove the powder which flows out into a more or less continuous coating akin to a coat of paint.
Powder for such use is manufactured by extruding the material in a large section to form an extruded solid stock. The solid stock is then kibbled into small pieces which are then ground into a powder.
The grinding process produces a wide range of particle sizes in the powder. Such a wide range would produce a very uneven coating and would make it impossible to produce a thin coating. To ameliorate that problem somewhat, the particles are graded to select a more uniform particle size. However, the problem remains that the particle size is rather too great easily to produce a high standard of finish suitable, for example, for motor cars.
One of the problems of kibbling and grinding is that the melting point of the material being processed must be high enough that the material is not melted during the kibbling and grinding process. Another problem in the known process for manufacturing powders is that producing stock by extrusion makes it uneconomic to produce small quantities of powder. A usual batch would be of the order of half a ton. Further, the extrusion, kibbling and grinding machinery is all large and expensive.